The present invention relates to vibration damping of structures and, more particularly, to the damping of two different frequencies of vibration in a structure by use of a single mass-spring-damper.
In my U.S. application, Ser. No. 08/241,755 filed May 12, 1994, now U.S. Pat. No. 5,431,261 granted Jul. 11, 1995. I have described in detail use of a dynamically controlled mass-spring-damper to damp a single frequency of excitation in a structure. This approach to reducing fatigue and failure in a monitored structure is highly beneficial.
However, most structures are subject to forces which cause them to vibrate at multiple frequencies, and generally two frequencies are of principal concern. Although the development of the patent application readily addresses the dominant frequency, the next most significant frequency of vibration may present a potential problem of only somewhat lesser magnitude.